1. it is difficult to search for it . Because infrared rays will never penetrate through earth atmosphere. 
2. we are unaware of how it looks like and we only know it is red and will glow . A damaged star also looks like this.
3. Dust also makes is hard to detect Dyson spheres . So we will get confused between Dyson sphere and a star surrounded by dust.
 
        
                    
             
        
        
        
Answer:
2,800 n
Explanation:
hope this helps, have a nice day/night! :D
 
        
             
        
        
        
Answer:
C.<u>ten</u><u> </u><u>times</u><u> </u><u>the</u><u> </u><u>intensity</u><u>.</u>
 
        
             
        
        
        
The blades that spin around in the fan, because they are flat and produce work